Question

In: Chemistry

KHP, C8H5O4K, is a weak acid and its formula weight is 204.22 g/mol. A sample of...

KHP, C8H5O4K, is a weak acid and its formula weight is 204.22 g/mol. A sample of impure KHP weighing 0.5000 grams was dissolved in 42.00 mL of 0.1000 M NaOH. The excess NaOH was back-titrated, requiring 32.00 mL of 0.1000 M HCl. What was the purity of the sample?

Expert Solution

Solution :-

Lets calculate the moles of the NaOH and HCl

Moles of NaOH = 0.1000 mol per L * 0.042 L = 0.0042 mol NaOH

Moles of HCl = 0.1000 mol per L * 0.032 L = 0.0032 mol HCl

So moles of the NaOH reacted with KHP = moles of NaOH – moles of HCl

= 0.0042 mol – 0.0032 mol

= 0.001 mol NaOH

Mole ratio of the KHP and NaOH is 1 : 1

So the moles of the KHP reacted = 0.001 mol

Now lets calculate the mass of KHP

Mass of KHP = moles * molar mass

= 0.001 mol * 204.22 g per mol

= 0.20422 g KHP

Now lets calculate the percent purity of the KHP in the impure sample

% purity = (mass of KHP / mass of sample) *100 5

= ( 0.20422 g / 0.5000 g) *100%

= 40.84 %

So the purity of the sample is 40.84 % pure

queen_honey_blossom answered 2 years ago

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